TSC:
Gerald S. emails, "Adam, I like your research and thoroughness that you present in your articles very much. In your Biotech Calendar: FDA Drug Approvals in 2011 article, I saw a number of companies with resubmissions upcoming in 2011. However, I wondered if you had updated the calendar, especially with any new companies or initial submissions and have you any information on a company named Vical(VICL_). They had a mishap with Sanofi-Aventis(SNY_) not long ago, but their vaccine allovectin-7 to treat metastatic melanoma is in Phase III. I respect your insight and opinion very much, and wonder what your take is on it."
Vical is conducting a phase III study in 390 patients with recurrent melanoma (skin cancer) who have not yet been treated with chemotherapy. The study compares treatment with allovectin to standard chemotherapy (dacarbazine or temozolomide) with a primary efficacy endpoint of durable response rate, defined as the response rate (tumor shrinkage) after 24 weeks of treatment.
Vical expects results from the allovectin study in the second half of the year.
Allovectin is touted as cancer "vaccine" because the drug is designed to stimulate a patients' immune system to identify and kill cancer cells. Yes, this is similar to how Dendreon's(DNDN_) Provenge works although allovectin is an off-the-shelf product made up of DNA sequences injected directly into the tumor. Once inside the tumor, Vical says allovectin triggers an immune response that has both local and systemic effects.
[Provenge, by comparison, works by mating a patients' own immune cells to a prostate cancer antigen. When the resulting "vaccine" is reinfused, the patient's immune system recognizes and attacks the prostate cancer cells.]
A previous single arm, open label phase II study of allovectin in 127 chemotherapy refractory patients yielded an 11.8% response rate, including four complete responses. This is generally equivalent to the melanoma response rate seen with dacarbazine in previous clinical trials.
Vical says the median duration of response to allovectin in the phase II study was almost 14 months and the median overall survival was about 19 months. View these data extra skeptically -- or perhaps disregard entirely -- since the phase II study lacked a comparator treatment, not even a placebo.
Dacarbazine and temozolomide are barely effective treatments for melanoma, so allovectin doesn't have a very high bar to hurdle in the phase III study. With that said, the marginal results from the phase II study don't provide much breathing room for allovectin to beat either of the two comparator drugs. Phase III studies rarely, if ever, produce better data than that seen in phase II studies. Measuring response after 24 weeks of treatment in the phase III study, presumably to allow for any immune response against the cancer to kick in, may help allovectin's chances. |
